1. Field of Invention
This invention relates to the management of printer resources in a print management system. In particular, this invention is directed to dynamic, preventive monitoring of printer resources, and centralizing the supervision of printer resources.
2. Description of Related Art
Print management systems provide a method for controlling and accessing various printers, as well as managing printer resources and other related information, from both proximate and remote locations. However, in the current print management systems, problems arising with printer resources, such as paper supply, toner or ink level, and drum quality, are not resolved until after the problems arise. For example, a system administrator or user located remotely from a printer is not aware of a "low paper" level for that printer until the paper tray is entirely empty. At that point, the printer will not operate until the paper supply is replenished. Thus, any print jobs already sent to the printer will not be printed until the paper supply is replenished. This problem is quite common and causes significant inconvenience and time delay.
As shown in FIG. 1, the basic conventional print management system 10 uses a client/server architecture that includes three primary components: a client 20, a server 40, and an output device 50. The client 20 conveys print and management requests to the server 40 and receives responses from the server 40 that arise in response to the submitted requests. In general, although not shown in FIG. 1, in these conventional print management systems, a large number of clients 20 will be connected to the server 40. Similarly, although not shown in FIG. 1, a large number of output devices 50 are usually connected to the server 40 and are located at widely distributed locations. The users of the clients 20 can include system administrators, system operators, and other end users.
The server 40 receives these requests from the clients 20, performs the required actions for each request, and returns the responses to the corresponding client 20. One such request from a client 20 is a print request, i.e., a request to print one or more copies of one or more documents, with the printed pages output using one or more features. The features can include simplex or duplex printing, stapling or binding, and the like. Thus, a print request represents a collection of one or more documents to be printed, as well as instructions for printing. The server 40 organizes the documents indicated in the print request submitted by the client into a print job. The server then sends the print job and any associated job control commands to the requested one of the output devices 50.
Each of the output devices 50 is a physical device, or hardware, that is capable of rendering images of documents and producing hard copy output of the print jobs received from the server 40. Each output device 50 can then return responses to the server 40 regarding its current state or the status of the received print jobs. The output device 50 is commonly a printer.
Recently, more efficient print management systems have been developed. The efficient distribution of print jobs in a print management system is described, for example, in U.S. patent application Ser. No. 08/966,404, filed Nov. 7, 1997, and incorporated herein by reference in its entirety.
As shown in FIG. 2, the incorporated '404 application discloses a network print management system 100. The network print management system 100 includes a network server 140, a number of clients 120 and a number of printers 150, although FIG. 2 shows only one such client 120 and printer 150. The network server 140 includes a spooler 142 and a supervisor 146. The supervisor 146 present on the network server 140 can detect and report printer problems, such as a paper jam or an empty paper tray. However, as discussed above, these problems are not detected and reported until after the problem has disabled the particular printer 150. A system administrator or user would then have to respond to the printer problem. Until the problem is resolved, the disabled printer 150 is inoperable. Thus, the network print management system 100 may become backlogged with print jobs. The print jobs already submitted to the disabled printer 150 will wait in the queue 144 until the problem is resolved.
Also, as shown in FIG. 2, the network print management system 100 includes a database 160 for storing system attributes. The term "attributes" refers to the characteristics of print jobs, documents, logical printers, and physical printers. The database 160 is used to store attributes representing fixed reference values, as well as attributes representing system characteristics that are continuously updated as the print management system dynamically changes.
Thus, the attributes are collections of data that describe the entities that form the network print management system 100. In other words, the attributes define or characterize print management systems abstract entities, or objects. For example, document attributes, such as plex, margin, orientation, etc., describe how the printed material should appear. Printer attributes, such as media-ready, fonts-ready, etc., describe the available resources or features of the printer. Other printer attributes may describe the various printing features that users may use to produce high-quality documents, or they may describe status or configuration information, such as the printer's state or location. In addition to these attributes, there are a suite of attributes to facilitate end user, operator and administrator functions. In summary, the attributes are a set of data that describes the objects of the printer management system 100.